An aircraft typically includes an electrical power system that generates and  supplies electrical power to various aircraft systems and subsystems. For example, the electrical power system may be operable to supply electrical power to lighting, avionics, passenger entertainment and flight control systems to enable the foregoing systems to perform their respective functions. The electrical power system generally includes one or more electrical alternators that are driven by the engines of the aircraft. The one or more alternators accordingly deliver alternating current (AC) to selected aircraft systems, and may also deliver direct current (DC) to other systems configured for DC, such as electrical storage batteries, by rectifying the AC generated by the alternators.
Since the power generated by the electrical alternators varies with the rotational speed of the armature within the alternators, changes in propulsive thrust from the engines generally result in variations in the power transferred to the various aircraft systems. In one known method, an aircraft alternator is coupled to a constant speed drive that includes a variable-output hydraulic pump that is driven by the engine of the aircraft. The hydraulic pump drives a hydraulic motor that is coupled to the alternator so that the alternator is driven at a relatively constant rotational speed. Accordingly, the alternator is operated at a relatively constant speed at various propulsive thrust settings by regulating the flow of hydraulic fluid to the hydraulic motor.
Although the foregoing system is effective to impart a relatively constant speed to the alternator so that a relatively constant voltage and frequency is provided to the various aircraft systems, it nevertheless exhibits significant disadvantages. For example, the added complexity of the foregoing system generally increases the amount of maintenance activity required to properly maintain the system. Since the added complexity may also contribute to a lower overall system reliability, dispatch efficiency may be adversely impacted. Since the foregoing system interposes a hydraulic drive mechanism between the engine and the alternator, the weight of the aircraft is also adversely affected.
Accordingly, what is needed in the art is a system and method for regulating electrical power distribution that is that is simpler than existing systems. Furthermore, in aircraft distribution systems, there is a continuing need for lighter and more reliable systems than are currently available.